note 110766 added to language.types.float

It seems that this hasn't yet been documented any well, but please be aware that displayed/printed values of floating point numbers are dependent on PHP configuration "precision". You might need to keep this in mind if you are doing tests with floating point numbers and want you test scripts always work under different situations. Following code tested with PHP 5.3.18 on a 64-bit machine: <?php for ($i = 15; $i < 19; $i++) { ini_set('precision', $i); echo sprintf('When PHP configuration "precision" is set to %2d, floating point number 1.12 is displayed as:', $i), "\n\t", 1.12, "\n\t", (string)1.12, "\n\t", round(1.12, 2), "\n"; echo "\tString ", (string)1.12, ' ((string)1.12) and ', (string)'1.12', " ((string)'1.12') are ", (string)1.12 == (string)'1.12' ? 'equal' : 'different', " when compared with '=='.\n"; // When PHP configuration 'precision' is set to different values, following expression prints different results! echo "\tString ", (string)1.12, ' ((string)1.12) and ', (string)'1.12', " ((string)'1.12') are ", (string)1.12 === (string)'1.12' ? 'equal' : 'different', " when compared with '==='.\n"; } ?> Output: When PHP configuration "precision" is set to 15, floating point number 1.12 is printed as: 1.12 1.12 1.12 String 1.12 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '=='. String 1.12 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '==='. When PHP configuration "precision" is set to 16, floating point number 1.12 is printed as: 1.12 1.12 1.12 String 1.12 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '=='. String 1.12 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '==='. When PHP configuration "precision" is set to 17, floating point number 1.12 is printed as: 1.1200000000000001 1.1200000000000001 1.1200000000000001 String 1.1200000000000001 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '=='. String 1.1200000000000001 ((string)1.12) and 1.12 ((string)'1.12') are different when compared with '==='. When PHP configuration "precision" is set to 18, floating point number 1.12 is printed as: 1.12000000000000011 1.12000000000000011 1.12000000000000011 String 1.12000000000000011 ((string)1.12) and 1.12 ((string)'1.12') are equal when compared with '=='. String 1.12000000000000011 ((string)1.12) and 1.12 ((string)'1.12') are different when compared with '==='. ---- Server IP: 69.147.83.199 Probable Submitter: 72.52.91.2 (proxied: 216.113.168.148) ---- Manual Page -- http://php.net/manual/en/language.types.float.php Edit -- https://master.php.net/note/edit/110766 Del: integrated -- https://master.php.net/note/delete/110766/integrated Del: useless -- https://master.php.net/note/delete/110766/useless Del: bad code -- https://master.php.net/note/delete/110766/bad+code Del: spam -- https://master.php.net/note/delete/110766/spam Del: non-english -- https://master.php.net/note/delete/110766/non-english Del: in docs -- https://master.php.net/note/delete/110766/in+docs Del: other reasons-- https://master.php.net/note/delete/110766 Reject -- https://master.php.net/note/reject/110766 Search -- https://master.php.net/manage/user-notes.php